FR2808916A1 - Active noise control unit for motor or engine includes oscillating baffle mounted within airflow conduit to exert dynamic effect on air flow - Google Patents

Abstract

An electro-dynamic or an electromagnetic motor (5) generates a reciprocating motion on an output shaft (4). A shaped element (3) is attached to the end of the output shaft in order to undergo reciprocating movement within the air flow (V). The shaped element (3) exerts a dynamic effect on the air flow. The electro-acoustic source comprises an electro-dynamic or an electromagnetic motor (5) generating a reciprocating motion on an output shaft (4). A shaped element (3) is attached to the end of the output shaft in order to undergo reciprocating movement within the air flow (V). The shaped element (3) exerts a dynamic effect on the air flow. The motor may be either a rotary or a linear device configured to produce a reciprocating movement. It may comprise an oscillating coil mounted within a magnetic induction field. The oscillating action may be provided by the action of a spiral spring which returns the shaft and hence the shaped element (3) to its rest position.

Description

The present invention relates to an electroacoustic source, as well as to an electroacoustic system comprising the application of such a source, this electroacoustic system source being in particular intended for active noise control in a confined flow.

The connecting ducts of alternative machines, such as compressors and heat engines, or the outlets of rotating propeller or turbine machines, such as fans and pumps, are the seat of fluctuations in the flow characteristics, which lead to aeroacoustic emissions themselves. same causing noise nuisance.

The latter can be attenuated in a passive way by means of so-called silent devices, often not very effective in the low sounds; because of their necessarily limited dimensions.

The attenuation of the noise emitted by the aforementioned fluctuations can also be effected by now well known methods of active absorption, using loudspeakers. However, the acoustic power required is very important, and the result is a great difficulty in implementing the loudspeakers, which must have very large dimensions. In addition, the loudspeakers, being lightweight mobile mechanical structures, do not have the acoustic impedance suitable for acting in a fluid line, which can also be the seat of a hot or corrosive flow, for example in output ducts of heat engines or refrigerating compressors.

The present invention aims to avoid these disadvantages, by providing a particularly effective device for the elimination of noise pollution, and can advantageously replace a speaker under conditions where it is hardly usable for the reasons mentioned above, and especially inside the pipes where a flow circulates.

For this purpose, the subject of the invention is essentially an electroacoustic source, consisting of an electrodynamic or electromagnetic motor means, capable of generating an oscillatory movement, and of at least one member coupled to said motor means, so as to describe a movement oscillatory, and adapted to be placed in a flow or border of a flow, obstructing the flow, so as to exert a dynamic action on this flow. The device which is the subject of the invention, referred to as the electroacoustic source, and defined above, is based on the following theoretical principle. The emission of an acoustic wave results, for a mobile wall, from the forces exerted by the wall on the fluid, the pressure fluctuations experienced by the wall constituting, for the surrounding wall fluid, a source of acoustic radiation. However, a flow exerts on an obstacle drag and lift forces proportional to the square of the speed. By giving this obstacle, by a suitable electrodynamic or electromagnetic means, a vibratory movement of translation or rotation, or a combination of these two types of movements, an acoustic source associated with the temporal variation of these forces is produced. The acoustic emission thus obtained has the same spectral content as the fluctuation of the preceding forces.

The electroacoustic source according to the invention, based on the general principles indicated above, comprises an obstacle forming member, of suitable shape, animated by an oscillatory movement which exerts a dynamic action on the flow in which it is placed. oscillatory movement is suitably controlled means such as rotary or linear electric motor, preferably oscillating, or by an oscillating member in a magnetic induction field, preferably an oscillating coil, this means being itself driven from a electrical signal, especially in the application to the realization of active noise control system.

The electroacoustic sources, produced according to the invention, can have significant powers, due to the amplifying effect of the flow for the fluctuating force exerted by the fluid on the wall of the obstacle member.

In order to fix the average position of this obstacle member, particularly in the case of such a member describing an oscillatory movement about an axis, it is advantageous to provide such means as a spiral spring or an elastic blade, creating an elastic return force. of said organ in its average position. Adjustment means may be provided for modifying the average position of the obstacle member and thus modifying its acoustic emission characteristics. According to a particular embodiment, these elastic return means also provide support for the obstacle member by defining a virtual axis of rotation. This arrangement is particularly advantageous in the case where the use of mechanical rotation bearings, such as ball bearings, is to be avoided; it is thus, in particular, when the electroacoustic source must operate in a hot and / or corrosive flow, such as refrigerant compressor fluids or combustion gases.

The electro-acoustic source, object of the invention, has different directivity properties, depending on the aerodynamic characteristics of the obstacle member, under the conditions in which this member is placed. The directivity of the acoustic emission of such a source fixed by the direction of the force exerted by the obstacle member on the fluid.

An obstacle member of profiled or unformed shape, mounted oscillating about an axis transverse to the direction of the flow, and creating a wake, has a directivity mainly oriented parallel to the direction of the flow, insofar as said obstacle member does not have lift.

An example of an obstacle member, as defined above, is a substantially rectangular oscillating flap, the oscillation axis preferably passing through the center of the flap.

Another example of an obstacle member, still having a directivity parallel to the direction of the flow, is an oscillating flap which bears on its leading edge and on its trailing edge of the curved walls, which prevent the gluing of the flange. flow on the wall of the flap and thus provide a wake width proportional to the angle of incidence, such as an S profile flap; this variant of the obstacle member is easier to manufacture industrially.

Electroacoustic sources, defined above, having a directivity mainly oriented parallel to the direction of flow, may be designated as axial electro-acoustic sources.

It is also possible to produce electroacoustic sources, in accordance with the invention, which have a directivity substantially perpendicular to the direction of flow, and which may be designated as transverse electroacoustic sources. Unlike axial sources, a transverse electro-acoustic acid source must have an obstacle member that has a high lift relative to the flow. Typical example of such a member is an oscillating flap having a wing profile.

The electroaero-acoustic sources previously defined being simple sources, it is possible to multiply them to produce a multiple electro-acousticoelectric source, associating two or more similar elementary electroacoustic sources, all of axial type or of transversal type; all these sources are arranged in the flow, in parallel or in series, or in a combination of these dispositions, and they are animated by the same oscillatory movement.

From electroaero-acoustic sources previously defined, it is also possible to produce complex electro-acoustic sources, which make it possible to obtain varied and specific effects, resulting on the one hand from the interaction of neighboring obstacles, fixed or mobile, and on the other hand different values of moments of inertia and aerodynamic forces, depending on the dimensions of the obstacles. In particular, complex electroacoustic sources can be obtained by associating a fixed obstacle with at least one axial or transverse electroaero-acoustic source (as defined above); by combining at least one axial electro-acousticoelectric source and at least one transverse electro-acoustic acid source, such that the main direction of the emission, which is the resultant of the drag and lift forces of the two sources respectively, is an oblique direction relative to the direction of flow.

The electroacoustic sources, defined above, have been related to an indefinite flow, except its direction, this flow may be either free or confined by walls, for example the walls of a pipe. Containment of the flow by walls offers the advantageous possibility of increasing the efficiency of the electro-acoustic sources defined above, by arranging such a source (single or multiple) at a suitable nozzle, locally creating a narrowing of the section. right of the pipe, thus the flow and accelerating the flow, thereby increasing the force exerted by the electro-acoustic source on this flow. Such a nozzle may be formed by a simple fixed profiled sleeve, inserted into the conduit traversed by the flow, the electro-acoustic acid source being disposed inside the sleeve, in the reduced section delimited by this sleeve. In a variant, the nozzle or sleeve decreasing the cross-section available for the flow is produced by means of movable walls, in particular articulated around an axis, associated with mechanical control means; the fixed but adjustable position given to these walls makes it possible to modify the section available for the passage of the flow, and thus to increase or reduce the speed of the flow at the level of the electro-acoustic source, which makes it possible to control at will the said source efficiency.

According to another variant, the electroacoustic source, located at the edge of the flow, comprises an obstacle member constituted by an oscillating wall portion confining the flow, this movable wall portion also forming a narrowing of the straight section of the flow. . In this embodiment, the obstacle oscillating member is located at the edge of the flow, and realizes the nozzle itself.

All electroacoustic sources, previously defined, can be implemented for active noise control, also known as active acoustic absorption, especially confined flow with configurations (nozzles) have just been indicated. In the context of this preferential application, the invention provides an electroacoustic system for active noise control, which essentially comprises at least one electroacoustic source as defined above, with an electrodynamic or electromagnetic motor means and an obstacle member placed in a flow or at the edge of a flow, and a controller driving said motor means, the controller itself being controlled from at least one microphone measuring the noise to be controlled.

In the case of such an electroacoustic system for active noise control using a single single electroacoustic source, or a plurality of identical elementary sources powered in parallel, the controller may be a single channel controller. In a system using two or more electro-acoustic sources of different characteristics or types, for example an axial source and a transverse source (as defined above), supplied separately, the controller will be a multi-channel type controller.

Electro-acoustic systems for active noise control, in accordance with the invention, can only use electro-acoustic acoustic sources as previously defined as active means of noise control, in which case they are systems. pure electroacoustics. Mixed systems are also conceivable, which use on the one hand at least one electroacoustic source, as previously defined, and on the other hand an active or passive means of noise attenuation operating according to a different principle.

Thus, a mixed system can comprise on the one hand minus an electro-acoustic source, and on the other hand a loudspeaker - the loudspeaker makes it possible to deal here with high frequencies, which the electroacoustic sources can hardly emit. The speaker is replaceable by another active means, such as electro-pneumatic source controlled.

As a passive means, associated with at least one electro-acoustic source, and more particularly a source placed in a nozzle (as defined above), a realization of the nozzle is advantageously provided by a sleeve of absorbent acoustic material. a semi-active system for the control of confined flow noise, in which the electro-acoustic acoustic source (s) process the low and medium frequencies, while the high frequencies are passively absorbed the aforementioned sleeve, of suitable material.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of example, embodiments of these electro-acoustic acoustic sources, and electro-acoustic systems for active control. FIG. 1 is a schematic diagram, in perspective, of an electroacoustic source according to the invention; Figure 2 is a side view of the figure source, placed in a free flow and constituting an axial source; Figure 3 is a view similar to Figure 2, but illustrating another arrangement of this axial source; Figure 4 is a perspective view of an electro-acoustic source according to the invention, of particular conformation; Figure 5 is a side view of the source of Figure 4; Figure 6 is a perspective view of another electro-acoustic source according to the invention, of particular configuration; FIG. 7 is a perspective view illustrating a particular assembly of an electroacoustic source, such as that of FIG. 6. FIG. 8 is a side view of an electroacoustic source such as that of FIG. 1, placed in a flow and constituting a transverse source; Figure 9 is a block diagram of a complex electro-acoustic acid source; Figure 10 is a block diagram of a multiple electroacoustic source; Figure 11 is a block diagram of another multiple electroacoustic source; Figures 12 and 13 illustrate examples of particular complex sources; Figure 14 shows, in perspective and in section, electro-acoustic source placed in a confined flow; Figure 15 is a schematic diagram of another source placed in a confined flow, and usable for active noise control; Figures 16, 17, 18, 19, 20 and 21 show, in the form of block diagrams, other examples of sources used for active noise control.

As shown in Figure 1, an electroacoustic source; generally designated 2, comprises a movable obstacle 3 mounted on the axis 4 of an electrodynamic or electromagnetic motor member, such as an oscillating electric motor or oscillating coil in a magnetic induction field, powered by a electric current, which can give the angle of the obstacle 3 an oscillation type variation. Such a device is placed in a fluid flow, of speed V, and the obstacle 3 animated by an oscillatory movement then exerts a dynamic action on the flow.

FIG. 2 shows an electroaeroacoustic source 2, as described above, placed in a free-speed flow V, the obstacle 3 forming a mean angle α with the direction of this flow, and thus creating a transverse dimension wake d. In the case of FIG. 3, the same obstacle 3 forms an average angle a greater than that, and it creates a wake of greater transverse dimension D. The drag force exerted by the velocity flow V on the obstacle 3 is stronger in the case of FIG. 3 than in FIG. 2, whereas the lift force has hardly changed for bearings where the flow is strongly off. F indicates the oscillatory force exerted by the obstacle 3 on the fluid. The directivity of the acoustic emission the electroeroacoustic source 2 is fixed by the direction of this force F; this directivity being mainly oriented parallel to flow direction, this is an axial source.

The obstacle 3 which essentially creates a wake, without significant lift effect, to obtain such an axial source FIGS. 4 to 7 illustrating examples of sources of particular profile meet these requirements.

According to FIGS. 4 and 5, the obstacle 3 is in the form of a rectangular oscillating flap 6, which carries on its leading edge a first curved wall 7, and on its trailing edge a second curved wall 8, the axis of the motor 5 passing through the middle of the flap 6. The curved walls 7 and 8 prevent the flowing of the flow on the flap wall 6, and thus provide a wake width proportional to the angle of incidence a.

According to FIG. 6, the obstacle 3 consists of a rectangular flap 9 whose leading and trailing edges are curved in opposite directions, as indicated at 10 and <B> 11, </ B> so as to give the strand 9 an S-shaped profile. The curved edges 10 and 1 1 are, here too, curved walls ensuring the desired wake, the latter conformation allowing, in addition, easier industrial manufacture of the obstacle 3.

FIG. 7 illustrates a particular assembly of the electroacoustic source 2, such as that of FIG. 6 with shutter 9 of S-profile. The axis 4, coinciding with the axis of symmetry of the flap 9, is supported by two bearings 12, each consisting of several leaf springs 13 fixed to a fixed portion 14, the leaf springs 13 serving as support for the axis 4, therefore at the obstacle 3, and resilient return means of this obstacle 3 in its average position, with respect to which it oscillates and produces a sound emission in interaction with the flow.

The return function of the profiled obstacle 3 in its average position can also be achieved by a simple spiral spring 15, this variant being illustrated in Figure 14 (described in detail below).

FIG. 8 shows another electroacoustic source 2 which, unlike the previous ones, constitutes a transverse source, that is to say that its directivity is substantially perpendicular to the direction of the flow, of velocity V. For this, the source 2 comprises an obstacle 3 with wing profile, always oscillating under the action of a motor, such an obstacle creating on the fluid a force F mainly due to the lift.

FIG. 9 illustrates a first so-called complex electro-acoustic acoustic source example, which consists of an axial source 2 with an obstacle 3 oscillating under the action of a motor as described above, which is placed in the vicinity of a fixed obstacle 16. The set of movable 3 and fixed obstacles 16 is placed in a flow of fluid, velocity V. The momentary increase in the incidence of the moving obstacle 3 causes an increase in the fluid velocity on the fixed obstacle 16, by deflecting the flow, which has the effect of increasing the pressure on this obstacle 16, in its instantaneous aeroacoustic emission. The set of two obstacles 3 and 16, one oscillating and motorized and the other fixed, thus constitutes an electro-acoustic source of specific structure and operation, and of superior efficiency to the source 2 alone, which is here a source axial.

FIG. 10 shows a so-called multiple electro-oacoustic source, which consists of several simple sources 2 as previously described. In this example, it is about three axial sources 2, connected in parallel in the same fluid flow, each source 2 comprising an oscillating flap 6 actuated by a motor 5. The three sources 2 are here identical in their shapes their dimensions, and animated by the same oscillatory movement. It will be noted that the replacement of a single electroacoustic source, giving a variation of wake width of given amplitude, synchronous synchronous electro-acoustic sources in parallel, reduced in size proportionally to the number n, makes it possible to obtain a torque n3 times smaller for each source and, in total, an electromechanical power n 'times smaller. In addition, the sound emission of sources thus grouped enhanced by their interaction effect, which is similar to that described above for the combination of a source 2 with an oscillating obstacle 3 and a fixed obstacle 16 (FIG. 9) .

As shown in FIG. 11, it is also possible to group several simple electroacoustic sources 2, 2 ', and 2 "of different characteristics, in particular of different dimensions adapted to the pulsations and amplitudes of different frequency bands, such complex source for obtaining various effects enhanced by the interaction of the flows around the respective obstacles 3, 3 'and 3 ". The lowest frequencies are for example realized with a source of greater scale than the average frequencies a fortiori, than the lowest frequencies. More particularly, FIG. 11 shows an embodiment of a complex electroacoustic source where the lowest pulsation is emitted by the source 2 'located in the middle, the average pulsation being mainly emitted by the lower source 2 ", while the high pulsation is produced. by the upper source 2.

FIG. 12 shows another embodiment of a complex electroacoustic source, which consists of a transverse source 2 with obstacle 3 oscillating under the action of a motor 5, which is placed in the vicinity of a fixed obstacle 17 of wing profile similar to that of the moving obstacle 3. The reinforcing effect of the fixed obstacle 17 is here analogous to that of the fixed obstacle 16 associated with an axial source in the example of FIG. 9.

FIG. 13 shows yet another embodiment of a complex electroero-acoustic source, which combines an axial source 2a and a transverse source 2b, so that the main direction of emission is in the oblique direction of the resultant R of the forces drag permutations T of the axial source 2a and lift of the transverse source 2b. Here, too, we obtain a reinforcing effect of the acoustic emission due to the interaction of the two respective obstacles 3a and 3b of the two sources 2a and placed in the same speed flow V.

In all of the examples described up to now, the electroacoustic sources are supposed to be placed in a free flow of indefinite transverse extent. On the contrary, Figures 14 and following represent electro-acoustic sources placed in a confined flow, that is to say, in practice, in line 18 traveled a fluid, whose speed is always indicated V. These sources are applied to control active noise.

FIG. 14 shows a simple electro-acousticoelectric source 2, produced as described above, with an oscillating obstacle 3 placed inside the pipe 18 traversed by the flow. More particularly, the oscillating obstacle 3 of this source 2 is placed in a nozzle 19, housed and fixed in the pipe 18, which locally locally reduces the cross section of the pipe 18, and thus accelerates the flow of the fluid and increases the force exerted by said source 2 on this flow. from this configuration, an electroacoustic system for active noise control is provided, by providing a controller 20 driving the motor 5 of the source 2, from a microphone 21 measuring the noise to be controlled, for example at the level of the wall driving 18.

Figures 15 and following illustrate various realizations of sources placed in confined flow, and applied to active noise control, according to the principle described above.

FIG. 15 shows an electroacoustic source 2 placed in a pipe 18, at the level of a nozzle made by means of walls 22 articulated each around an axis 23. The nozzle again decreases the available cross-section for the flow, and in this case a suitable mechanical control device (not shown) is used to rotate movable walls 22 and change their position, so as to adjust the section available for flow. By increasing the obstruction of the section, by approaching the movable walls 22, the efficiency of the source 2 is increased, for a given oscillation amplitude of its flap 9. It may be advantageous to erase the movable walls 22, when it is desired not to put the electroacoustic source 2 into action. Furthermore, FIG. 15 shows the active noise control system with its single channel controller 20, in connection with the source engine 5, with a control microphone 21 and also with a reference microphone 24, both microphones 21 and 24 being placed inside the pipe 18, respectively downstream and upstream of the source 2.

FIG. 16, in which the elements corresponding to those previously described are designated by the same reference numerals, shows a multiple electroacoustic source, comprising two identical single sources 2 arranged in parallel. The multiple source thus constituted is placed in line 18, at a nozzle 19. The single-channel controller supplies synchronously here the motors 5 of the two simple sources 2.

FIG. 17 represents an active noise control system, using a complex source resulting from two simple electroaero-acoustic sources 2a and 2b, respectively axial and transverse, arranged in series inside the duct 18, at the level of the nozzle 19. two sources 2a and 2b are fed separately, by a multi-channel type controller 20 receiving the signals of two control microphones 21a and 21b and two reference microphones 24a and 24b.

As shown in FIG. 18, the active noise control system may implement an actuator of a different principle, in particular a loudspeaker 25. The electroacoustic source is placed in line 18, at the level of the nozzle 19 The loudspeaker 25 is placed on the wall of the pipe 18. A multi-channel controller supplies separately the motor 5 of the source 2, and the loudspeaker 25. The latter makes it possible to treat high frequencies, that the electroacoustic source 2 can hardly emit. This active noise control system can especially be applied to ventilation devices, where the usually non-corrosive environment allows the insertion of loudspeakers.

In the examples of FIGS. 14, 16, 17 and 18, the nozzle 19 is generally cylindrical in shape and results from a fixed profiled sleeve inserted in line 18 traversed by the flow, this sleeve being solid, or at least with a wall full.

Figures 19 and 20 illustrate variants in which the nozzle 19 consists of a fixed profiled sleeve, made of absorbent acoustic material 26 can be contained in a shell 27 perforated wall. In the configuration of Figure 19, the electroacoustic source 2, which is a simple source, processes the low frequencies, while the nozzle 19 of special constitution absorbs the high frequencies. In the configuration of FIG. 20, the low and medium frequencies are processed by the complex electroacoustic source consisting of the two single sources 2 and 2 'in parallel controlled by single channel controller 20, while the high frequencies are passively absorbed by the Absorbent acoustic material 26 of the nozzle 19. The assembly thus constitutes a semi-active confined flow circuit control system.

Finally, FIG. 21 shows another embodiment of the invention, in which the pipe 18 comprises a portion 28 which makes a narrowing of the cross-section available for flow, this portion 28 being constituted by flexible walls capable of to be animated by a vibratory movement by means of electromagnets 29 placed outside the pipe 18. The movable walls 28 here play the role of the oscillating obstacle of the previous exemplary embodiments.

Note that the configuration of Fig. 21 creates a pressure difference due to the existence of swirling wakes T in the sudden widening of the cross-section following the resulting shrinkage of shape of the movable walls 28. Indeed, as already explained more high, the axial acoustic effect is virtually zero if the obstacle is a shaped obstacle for which no detachment is observed.

It goes without saying that the invention is not limited to the embodiments of electroacoustic sources, and electroacoustic systems for active noise control, which have been described above, by way of example; it embraces, on the contrary, all variants of implementation and application respecting the same principle. It is thus, in particular, that one would not depart from the scope of the invention - in the case of a multiple electroacoustic source, by increasing or reducing the number of associated single sources; - in the case of an active noise control system, by disposing in the conduct any form of single or multiple or complex electro-acoustic source as described and illustrated in the drawing, and using any appropriate arrangements of control microphones and; possibly reference microphones.

Claims (23)

<B> <U> CLAIMS </ U> </ B> 1. Electro-acousous source, characterized in that it consists of an electrodynamic or electromagnetic motor means (5), capable of generating an oscillatory movement, and of at least one member (3) coupled to said motor means, so as to describe an oscillatory movement, and able to be placed in a flow (V) or border of a flow, obstructing the flow, so as to exert a dynamic action on this flow. 2. électroéroacoustic source according to claim 1, characterized in that the motor means (5) is a linear rotary electric motor, preferably oscillating. 3. électroéroacoustic source according to claim 1, characterized in that the motor means (5) is an oscillating member in a magnetic induction field, preferably an oscillating coil. 4. Electroerocoustic source according to any one of claims 1 to 3, characterized in that are provided for fixing the average position of the member (3) forming an obstacle, including such a member describing an oscillatory movement about an axis (4), means such as spiral spring (15) or elastic blade (13) creating an elastic return force of said member (3) in its average position. 5. électroéroacoustic source according to claim 4, characterized in that the elastic return means (13) also provide support for the member (3) forming an obstacle, defining a virtual axis of rotation (4). 6. électroéroacoustic source according to claim 4 or 5, characterized in that means for adjusting the average position of the member (3) forming an obstacle are provided to modify its acoustic emission characteristics. 7. Electro-energetic source according to any one of claims 1 to 6, characterized in that it comprises a member (3) forming an obstacle shaped or non-profiled, mounted oscillating about axis (4) transverse to the direction of the flow (V), and creating a wake, which has a directivity mainly oriented parallel to the direction of the flow (V), so as to constitute an electro-acousticoelectric source (2) axial. 8. electro-acousticoelectric source according to claim 1, characterized in that the obstacle member (3) is a substantially rectangular oscillating flap (6), the oscillation axis (4) passing preferably through the center of inertia of the flap ( 6). 9. électroéroacoustic source according to claim characterized in that the member (3) forming an obstacle is a flap (6; 9) which bears on its leading edge and on its trailing edge curved walls 8; 10, 1), such as an oscillating flap (9) of S-shaped profile. 10. Electroacoustic source according to any one of claims 1 to 6, characterized in that it comprises a member (3) forming an obstacle which has a high lift relative to the flow (V), such as an oscillating flap having a wing profile, and which thus has a directivity substantially perpendicular to the direction of the flow (V), so as to constitute a transverse electroaeroacoustic source (2). 11. Electro-acousous source according to any one of claims 1 to 10, characterized in that it is designed as a complex electro-acoustic source associating a fixed obstacle (16; 17) to at least one electro-acoustic (2) axial or transverse source. 12. electro-acousticoelectric source according to any one of claims 1 to 10, characterized in that it is designed as a multiple electroacoustic source, combining two or more electroeroacoustic sources (2) elementary similar, axial type or transverse type, all these sources (2) being arranged in the flow (V) in parallel or in series or in a combination of these arrangements, and being animated by the same oscillatory movement. 13. electro-acousticoelectric source according to any one of claims 1 to 10, characterized in that it is designed as a complex electro-acoustic acid source, combining at least one axial electro-acoustic acid source (2a) and at least one transverse electro-acoustic acid source (2b), such that the main direction of emission (R) is oblique with respect to the direction of flow (V). 14. électroéroacoustic source according to any one of claims 1 to 13, characterized in that it is placed in a flow (V) confined, in particular in a pipe (18). 15. electroacoustic source according to claim 14, characterized in that it is disposed at a nozzle (19) or a fixed profiled sleeve, inserted in a pipe (18) traversed by the flow (V) for locally create a narrowing of the cross section this flow (V). 16. electroacoustic source according to claim 15, characterized in that the nozzle or the sleeve made by means of movable walls (22), in particular articulated about an axis (23), associated with mechanical control means, so that that the section available for passage of the flow (V) can be modified. 17. electroacoustic source according to claim 14, characterized in that it is located at the edge of the flow (V), and in that it comprises an obstacle member constituted by an oscillating wall portion (28) confining the flow (V), said movable wall portion (28) also making a narrowing of the cross section of the flow (V). 18. Electro-acoustic system for active noise control in open or confined space, characterized in that it comprises at least one electro-acoustic source (2) according to any one of claims 1 to 17, with an electrodynamic motor means (5) or electromagnetic device and an obstacle member (3) placed in a flow (V) or at the edge of a flow, as well as a controller (20) driving said motor means (5), the controller (20) being itself driven by from at least one microphone (21) measuring the noise to be controlled. Electro-acoustic acoustic control system according to claim 18, characterized in that a single electro-acoustic source (2) or a plurality of identical single sources fed in parallel is used, the controller (20) being of the single-channel type. . 20. électroaéroacoustique system for active noise control according to claim 18, characterized in that it uses two or more electro-acoustic sources of different characteristics or types, for example an axial source (2a) and a transverse source (2b), fed separately the controller (20) being of the multichannel type. 21. electroacoustic system for active noise control according to any one of claims 18 to 20, characterized in that it uses on the one hand at least one electroacoustic source (2), and on the other hand an active means ( 25) or passive (26) noise attenuation operating according to a different principle. 22. electroacoustic system for noise control according to claim 21, characterized in that it comprises at least electro-acoustic source (2) and as other active means, a speaker (25). 23. electroacoustic system for active noise control according to claim 21, characterized in that it comprises at least one electro-acousticoelectric source (2) placed in a nozzle (19) according to claim 15 and, as passive means, the sleeve constituting the nozzle (9), made of absorbent acoustic material (26).